Unit 4 Flashcards
(27 cards)
Describe an aseptic technique to transfer a liquid culture from a bottle onto a agar plate
-Use a sterile pipette
-Remove the lid off the bottle and flame the lid
-Lift the lid of the agar plate at an angle
-Use a sterile spreader
define a locus
the location of a particular gene on a chromosome
define an allele
different versions of genes
define a homologous pair of chromosomes
-a pair of chromosomes that have exactly the same genes, are the same size but may have different alleles
What is the function of a histone protein
-to associate with the DNA to assist in the tightly coiling of DNA to fit chromosomes into the nucleus
why is the genetic code described as universal
-the same base triplet codes for the same amino acid in all organisms
define a gene
-a base sequence of DNA that codes for the amino acid sequence of a polypeptide
Why is the genetic code described as degenerate
-there are more than one triplet of bases that code for the same amino acid
why is the genetic code described as non-overlapping
-each base in a gene is only part of one base triplet that codes for one amino acid
what is a start codon
-three bases at the start of every gene that initiate translation
what is a stop codon
-three bases at the end of every gene that cause ribosomes to detach and therefore stop translation
what is a gene mutation
-a change in the base sequence of DNA
Explain crossing over
-homologous pairs of chromosomes associate and form a biavalent
-chiasmata forms
-equal lengths of non sister alleles are exchanged
-producing new combinations of alleles
compare the differences between mitosis and meiosis
-mitosis has one nuclear division whilst meiosis has two
-mitosis produces diploid cells whilst meiosis produces haploid cells
-mitosis created genetically identical cells whilst meiosis introduces genetic diversity
define genetic diversity
-the number of different alleles of genes in a population
explain natural selection
-a mutation occurs forming a new allele and giving the possessor an advantage
-due to the advantageous allele the organism has increased survival and reproductive success
-the advantageous allele is passed onto offspring
-over time over many generation the frequency of the advantageous allele will increase
define evolution
-the change in allele frequency over many generations in a population
define species
-organisms that are able to breed and produce fertile offspring
order the classification heirachy system
-domain
-kingdom
-phylum
-class
-order
-family
-genus
-species
define biodiversity
-the variety of organisms living in the area
define a habitat
-the place where an organism live
define a community
-all the populations of different species in a habitat
define species richness
-a measure of the number of different species in a community
explain why removing hedgerows/woodland reduces biodiversity
-less habitats so less variety of food sources
